High charging voltage

**twincaman** · 01-07-2019, 04:43 PM

1992 Black Max 2.5 litre 175hp having a chronic problem with high charging voltage. I have replaced both regulators with brand new CDI units and the stator looks fine. My voltage reads 15v at idle and 15.5-15.8 at 2000rpm. I have a 2 battery system with a 3 way switch between and voltage is the same with either or both batteries in line. I just replaced the batteries which made no difference. Is that voltage acceptable? The batteries do not seem to be overheating and I can bring the voltage down to 14 or 14.5 by playing the stereo (with amp) at high volume. Heh.

Any ideas? Advice?

**Tritontr19** · 01-07-2019, 06:03 PM

Be sure gauge is correct, and if they are maint free batteries that may cause it. Clay

**twincaman** · 01-07-2019, 06:35 PM

Yes they are maintenance free 800 amp cold crank batteries. Any idea if I will fry the batteries or start a fire running with this charging voltage? Don't wanna damage anything and I will keep investigating if I have to. This boat, never in salt water, and its 3 way battery switch is 26 years old, so.......... The starter motor seems to crank very briskly so I think the switch must be OK, but ...... Mystified

**Dave Strong** · 01-08-2019, 01:20 PM

Check the voltage with a known good meter, AGM batteries are no good on that style charging system need to be lead acid. Look for poor, corroded or high resistance cable. Ohm test the stator as well.

Dave

**twincaman** · 01-08-2019, 04:51 PM

Voltage tested with good multimeter are 14.4 at the batteries and 14.9 at the starter solenoid at idle and 15.5 at the starter solenoid at 2000 rpm. Batteries both read 12.5 v with engine off. I've used maintenance free agm batteries forever on this boat. I'm just wondering if I'm being too fussy about this and should just accept the slightly high voltage as long as the batteries don't overheat.

BTW, Thanks for the responses.